Protective shelter installation

ABSTRACT

A protective shelter such as a bomb shelter can be entered into or left through an elongate tunnel connected with an enclosed shelter area and including at least two spaced apart angle sections formed by correspondingly curved side walls of the tunnel. The curved tunnel sections serve to prevent the build-up of a destructive pressure head in the tunnel. The walls of the tunnels are constructed of prefabricated concrete blocks joined in situ by suitable screw connections.

United States Patent 1191 Ludwig 1 1 Jan. 9, 1973 [s41 PROTECTIVE SHELTER 2,622,937 12/1952 Taylor ..138/172 INSTALLATION 3,173,387 3/1965 Cree ..109/1 s 3,347,187 10/1967 Khoury ..312/245 [76] Inventor: Gustav Ludwig, Saganer strasse 1,

Nurnberg, Germany FOREIGN PATENTS OR APPLlCATlONS {22] Filed: Feb. 10, 1970 203,942 5/1966 Sweden ..52/493 [2]] Appl No 10145 1,031,666 6/1966 GreatBritain ..109/1 S Primary Examiner-Reinaldo P. Machado [30] Foreign Application Priority Data Attorney-Hane Baxley Feb. 15, 1969 Germany ..P 19 07 733.9 57 ABSTRACT 52 us. c1 ..109/1 s A Protective Shelter Such as a b Shelter can be [51] Int CL E0411 9/12 tered into or left through an elongate tunnelv con- [58] Field of 169 nected with an enclosed shelter area and including at v g [172 least two spaced apart angle sections formed by correspondingly curved side walls of the tunnel. The curved tunnel sections serve to prevent the build-up of [56] References'clted a destructive pressure head in the tunnel. The walls of UNITED STATES PATENTS the tunnels are constructed of prefabricated concrete blocks joined in situ by suitable screw connections. 3,464,374 9/1969 Basler ..109/1 S 1,486,152 3/1924 Mascio ..52/584 7 Claims, 8 Drawing Figures PROTECTIVE SHELTER INSTALLATION The invention relates to a protective shelter installation such as an air raid shelter or bomb shelter and more particularly to the entrance and exit tunnel of such installation.

BACKGROUND Entrance and exit tunnels for protective shelter installations of the general kind above referred to are usually connected with the enclosed area of the shelter through an air lock with filter assembly and includea right angle section. There is also usually provided an emergency exit. Shelter installations with a tunnel of this kind as heretofore known have the disadvantage that shock waves of anuexplosion entering the tunnel are reflected back towardthe entrance of the tunnel at the right angle section and are, again pressed into the right angle-section by a subsequent shock wave. As a result, a high pressure head will be built up'in the tunnel and such pressure head may cause a collapse of the tunnel at its angular section.

Another disadvantage of shelter installations as heretofore known is that the concrete walls customarily used for constructing the tunnel walls are molded in situ. Such in situ construction makes it virtually impossible to avoid the presence of cavities in the concrete and also the presence of cracks or gaps between parts of the walls. Areas of the walls including such cavities and/ or gaps or cracks are particularly likely to collapse as the destructive force of a pressure head will be particularly damaging at such inherently weakened areas.

Obviously, destruction or blockage of the tunnel of the shelter due to the formation of a pressure head as previously described, makes it difficult or even impossible for persons seeking protection in the shelterto leave the same so that the purpose of a shelter to save lives is largely defeated.

THE INVENTION It is an object of the invention to provide a novel and improved tunnel for a shelter installation of the kind above referred to which is so constructed that it will not be destroyed by a pressure head as caused by successive shock waves; I

A more specific object of the invention is to provide 2 SUMMARY OF THE INVENTION The afore pointed out objects; features and advantages .and other objects, features and advantages which will be pointed out hereinafter and are set forth in the appended claims are obtained by including in each tunnel leading into and out of the shelter area proper at least two spaced apart anglesections formed by curved sidewalls. As a result, a pressure or shock wave is. deflected within the tunnel rather than reflected back thereby avoiding a collision with a subsequent shock or pressure wave and thus a build-up of a dangerous pressure head within the tunnel.

According to another aspect of the invention, the tunnel walls are constructed of pre-fabricated blocks which are joined to each other by connectors embedded inthe blocks. A heat refractory and also gas, moisture and radiation tight seal is preferably interposed between each two blocks. The use of prefabricated blocks such as concrete blocks has the advantage that thepresence of cavities can be effectively avoided. While cavities are virtually unavoidable when the concrete walls are molded in situ, blocks which are pre-fabricated in a plant can be more easily and accurately checked as to flaws. Moreover, the hardness and other critical qualities of the blocks can be readily tested before the blocks are installed. Blocks can also be produced in the plant at lower cost than in situ. Prefabrication-of the block-s further permits construction of any desired shapes and angles of the tunnel walls not only of right angles at economicallyacceptable costs. Moreover, any length of the tunnel and any grade along the length of the tunnel can be more conveniently constructed with pre-fabricated blocks than when the walls are produced in situ. Finally, pre-fabricated blocks can bemore accurately manufactured for a selected pressure resistance than walls built in situ.

The pre-fabricated blocks as stated before are joined I to each other by means of flanges formed in the same andcouplers such as' screw connections so that the blocks arejoined to each other rigid against tilting rela tive to each other, and also gas, moistureand radiation tight.

An air lock, filters and provision of an emergency exit between the tunnel and the enclosed she lter area proper can be provided in a conventional and proven suitable screw connections thereby eliminating the inherent weakness of in situ constructed'concrete walls as are heretofore customary.

Still another more specific object of the invention is to provide a novel andimproved shelter installation of the kind above referred to in which the joints between adjacent building blocks are gas, moisture and radiation tight sealed by an also heat refractory sealing material. i

manner. v

. DETAILED DESCRIPTION OF THE INVENTION In the accompanying drawing several embodiments of the invention are shown by way of illustration and not by way of limitation.

In the drawing:

FIG. 1 isa sectional lengthwise plan view of a tunnel including two angle sections;

FIG. 7 is a fragmentary,sectional,vertical view of still another connection between two adjacent building blocks; and

FIG. 8 is a front view of a building block as used for construction of the tunnel.

Referring now to the figures more in detail, the exemplified shelter installation of FIG. 1 does not show the shelter area proper as the same does not constitute part of the invention but only diagrammatically an air lock a leading into and out of the shelter area proper.

The tunnel according to the invention includes at least two angle sections shown by way of example as right angle sections and d. A straight tunnel section b leads to angle section c which is joined to angle section d by a straight section e. As is shown, the angle sections are formed by correspondingly curved side walls.

As is evident, a shock wave entering the tunnel through section b will not be reflected back by section c due to the curved side walls thereof but will be deflected, at least partly, into section e. Accordingly, the afore described dangerous and possibly destructive build up of a pressure head in section c due to a subsequent shock wave cannot occur. The same is true also for a shock wave propagated to curved section d through straight section 2. Careful calculations have shown that the force of successive shock waves is dissipated to an extent such that there is no likelihood of collapse of the tunnel in the areas of sections c and d.

As previously pointed out, the tunnel is constructed of individual pre-fabricated building units as best shown in FIG. 4, that is, each individual building unit consists of a one-piece pre-fabricated block such as a concrete block. Each of the blocks forms the side walls, the bottom wall and the roof of the respective building unit. The block e, of FIG. 8 may be visualized as constituting the entrance block into tunnel section b. As previously pointed out, such prefabricated blocks can be conveniently and thoroughly checked in the plant as to flaws and stress resistance.

The blocks are joined to each other by suitable couplers or connectors. As is shown in FIG, 5, which is a crosswise section through two adjacent blocks a flange 0 is formed in each of the two blocks by meansof recesses s. Aligned holes through the flanges, preferably lined by an internally threaded liner 1', accommodate screw bolts g. Tightening of thebolts by nuts h will pull the two blocks strongly together. Gas, moisture and radiation impervious and also heat refractory sealing material f such as strings of asbestos are preferably interposed between the facing sides of the blocks.

FIG. 6 shows a coupler in which a recess k has generally horizontal extension k, into which the bolts are laterally inserted and then tightened.

FIG. 7 shows a coupler in which the bolts g extend through flanges formed by adjacent recesses I.

As is shown in FIGS. 2 and 3, the tunnel may include a grade which is bridged by suitably slanted building blocks m leading from the higher level to the lower level of the tunnel. Blocks m may be formed with steps n.

An installation according to the invention may, of course, also be used as a bunker for combat purposes.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention, it Wlll be understood by those skilled in the art, after understanding the invention,

that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed is:

l. A shock wave resistant entrance and exit structure angle section leading to the shelter area, and an airlock at said other end of the second angle section.

2. The structure according to claim 1 wherein said two angle sections comprise substantiallyright angle sections.

3. The structure according to claim 1 .wherein said straight tunnel section includes portions located at different levels with reference to a horizontal reference level. I

4. The structure according to claim I wherein the walls of said tunnel are composed of pre-fabricated one-piece concrete blocks each constituting a complete length of the tunnel, and wherein coupling means secure each two adjacent ones of said blocks together and a seal made of a gas, moisture and radiation impervious heat refractory material is interposed between each two adjacent blocks at the sides thereof secured to each other by said coupling means.

5. The structure according to claim 4 wherein each of said coupling means comprises a recess in each of two adjacent blocks, each of said recesses defining a flange in the respective block, said flanges facing each other and including at least one crosswise hole extending through both flanges in alignment, and wherein a screw connection extends into said aligned holes thereby securing the respective blocks to each other.

6. The structureaccording to claim 5 wherein a threaded liner made of a hard material is provided in said holes lining the same and receiving said screw connection.

7. The structure according to claim 4 wherein said coupling means comprise a recess formed in each of two adjacent blocks, said recesses defining two juxtaposed flanges at the facing sides of said adjacent blocks, wall portions of the blocks defining the recesses including slots aligned with each other, and wherein a screw connection is fitted in said slots thereby securing the blocks to each other. 

1. A shock wave resistant entrance and exit structure of an underground shelter area comprising: an elongate entrance and exit tunnel for a shelter area, said tunnel including along its length at least two oppositely facing angle sections formed by curved side walls and a substantially straight section intermediate the angle sections separating the angle sections, said straight section joining the adjacent ends of the angle sections, the other end of one angle section constituting the entrance and exit end of the tunnel and the other of the second angle section leading to the shelter area, and an airlock at said other end of the second angle section.
 2. The structure according to claim 1 wherein said two angle sections comprise substantially right angle sections.
 3. The structure according to claim 1 wherein said straight tunnel section includes portions located at different levels with reference to a horizontal reference level.
 4. The structure according to claim 1 wherein the walls of said tunnel are composed of pre-fabricated one-piece concrete blocks each constituting a complete length of the tunnel, and wherein coupling means secure each two adjacent ones of said blocks together and a seal made of a gas, moisture and radiation impervious heat refractory material is interposed between each two adjacent blocks at the sides thereof secured to each other by said coupling means.
 5. The structure according to claim 4 wherein each of said coupling means comprises a recess in each of two adjacent blocks, each of said recesses defining a flange in the respective block, said flanges facing each other and including at least one crosswise hole extending through both flanges in alignment, and wherein a screw connection extends into said aligned holes thereby securing the respective blocks to each other.
 6. The structure according to claim 5 wherein a threaded liner made of a hard material is provided in said holes lining the same and receiving said screw connection.
 7. The structure according to claim 4 wherein said coupling means comprise a recess formed in each of two adjacent blocks, said recesses defining two juxtaposed flanges at the facing sides of said adjacent blocks, wall portions of the blocks defining the recesses including slots aligned with each other, and wherein a screw connection is fitted in said slots thereby securing the blocks to each other. 